Field Sobriety Test

Prosecutors try to prove guilt in a drunk driving case in several different ways. One method is to prove impairment by introducing evidence that the driver failed to successfully perform the Standardized Field Sobriety Test (SFST) administered by the arresting officer. In Wisconsin OWI cases, police officers can administer a field sobriety test if they have a reasonable suspicion that the driver is intoxicated by alcohol or some other drug.

In Wisconsin OWI cases, there are generally three standardized tests, plus a Preliminary Breath Test.

Horizontal Gaze Nystagmus Test (HGN)

This is usually the first field sobriety test that police officers will administer.

The officer asks the driver to hold his or her head still and follow an object, usually the officer’s finger or a pen, as they move it left to right. The officer checks to see that the eyes track smoothly with the object and then they check for nystagmus when the object is positioned at a 45-degree angle.

Nystagmus is a bouncing of the eye at this position. It indicates to the officer that the driver is impaired.

The test is considered to be accurate — however, officers rarely administer the test properly. What is worse, is that there is no way to verify the observations that are being made by the officer.

An attorney can challenge the admissibility of the test and advance that the test should not be considered because it was not performed properly.

Walk and Turn Test

In this test, the driver is asked to walk a straight and imaginary line while positioning their arms at their side. They are told to take nine steps, turn around using a series of smaller steps, and then take another nine steps in the opposite direction.

The officer observes whether the driver follows instructions and performs the test without stepping off the line or using their arms for balance.

Most OWI arrests now include video preservation of the tests, allowing the attorney to verify whether the test was administered properly and whether the driver performed the test sufficiently to demonstrate the absence of intoxication.

One Leg Stand Test

The last test performed in Wisconsin OWI cases is the One Leg Stand.

Here the officer asks the driver to stand still with his or her arms at their side. They are asked to raise one leg and count until the officer tells them to stop.

If the driver puts their foot down, stumbles, or fails to count properly, they will fail the test.

Preliminary Breath Test (PBT)

After all the tests have been performed, the officer usually asks the driver to take a Preliminary Breath Test, or PBT. The PBT tests how much alcohol is present in the driver’s blood.

This is not considered part of the Standardized Field Sobriety Tests, but is often administered in conjunction with them. The officer can consider the result when deciding whether to make an arrest.

The result of PBT is not admissible in court to prove an OWI case.

OWI attorney Robert W. Keller aggressively cross-examines police officers to show that their testing methods are unreliable and inaccurate when determining whether someone is intoxicated. In many cases, the driver’s performance on these tests can be used to show that they were not intoxicated.